Abstract: Three frequecy band's Q^-1_c of four earthquake sequences in Yunnan Area, Yao'an M6.5 sequence in 2000, Shidian M5 sequences in 2001, Yongsheng M6 sequence in 2001 and Dayao M6.2, M6.1 sequence in 2003, are calculated with vertical digital seismogram in stations around the sequences. By analyzing and comparing their temporal characteristics, we conclude that Q^-1_c values to be stable after the main shock for mainshock-aftershock sequences; but for mainshock swarm sequences, Q^-1_c values would trend to be increasing at first after the first main shock then decreasing and after a short time lasting the next main earthquake occurs. Those tendencies show rough agreements for Q^-1_c in stations around the sequences and three frequency bands except their amplitudes show varying, which would be related to the zone of earthquake generation and the progress of stress accumulation. This research provides a new way to predict strong aftershocks.

Key words: Earthquake sequence, Q^-1_c, Yunnan Area